When relaoding a shader that keeps erroring, Unity 2018.1 sometimes crashes.

Repro steps:

- Use Scene 3
- Open testy.shader with Visual Studio and modify the shader
- From time to time, click back to Unity and try to see the changes.
- The 4th of 5th time Unit tries to recompile the shader, I get a crash
- also crashes on Unity 2017.4

This is the second time this happened. Same repro steps

========== OUTPUTTING STACK TRACE ==================

0x00007FFC2675616D (igc64) OpenOGLCompiler
0x00007FFC26756096 (igc64) OpenOGLCompiler
0x00007FFC26C7DAC6 (igc64) getJITVersion
0x00007FFC26C7DC1F (igc64) getJITVersion
0x00007FFC26C7DE8F (igc64) getJITVersion
0x00007FFC26C7D580 (igc64) getJITVersion
0x00007FFC26E86693 (igc64) OpenCompiler12
0x00007FFC26E57C5A (igc64) OpenCompiler12
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FFC287AFA64)
0x00007FFC287AFA64 (igd10iumd64) (function-name not available)
0x00007FFC28F7812D (igd10iumd64) GTPIN_IGC_Instrument
0x0000000141EF6875 (Unity) GfxDeviceD3D11Base::BeforeDrawCall
0x0000000141EFD0DB (Unity) GfxDeviceD3D11Base::DrawBuffers
0x0000000141F7071C (Unity) GfxDeviceWorker::RunCommand
0x0000000141F729FB (Unity) GfxDeviceWorker::RunExt
0x0000000141F72B28 (Unity) GfxDeviceWorker::RunGfxDeviceWorker
0x0000000140A74FB8 (Unity) Thread::RunThreadWrapper
0x00007FFC3AB61FE4 (KERNEL32) BaseThreadInitThunk
0x00007FFC3CD8F061 (ntdll) RtlUserThreadStart

========== END OF STACKTRACE ===========

NOTE: i tried to open the same project again with Unity 2018.1 and it crashed again straight away. Similar Stack trace.

========== OUTPUTTING STACK TRACE ==================

0x00007FFC2675616D (igc64) OpenOGLCompiler
0x00007FFC26756096 (igc64) OpenOGLCompiler
0x00007FFC26C7DAC6 (igc64) getJITVersion
0x00007FFC26C7DC1F (igc64) getJITVersion
0x00007FFC26C7DE8F (igc64) getJITVersion
0x00007FFC26C7D580 (igc64) getJITVersion
0x00007FFC26E86693 (igc64) OpenCompiler12
0x00007FFC26E57C5A (igc64) OpenCompiler12
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FFC287AFA64)
0x00007FFC287AFA64 (igd10iumd64) (function-name not available)
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FFC2879FCB0)
0x00007FFC2879FCB0 (igd10iumd64) (function-name not available)
ERROR: SymGetSymFromAddr64, GetLastError: 'Attempt to access invalid address.' (Address: 00007FFC28EF40B0)
0x00007FFC28EF40B0 (igd10iumd64) (function-name not available)
0x00007FFC3AB61FE4 (KERNEL32) BaseThreadInitThunk
0x00007FFC3CD8F061 (ntdll) RtlUserThreadStart

========== END OF STACKTRACE ===========